Rationale

I have just obtained an international standard in ISO for stormwater chambers (ISO 4982) that should be published in the coming months, and I managed to get ASTM F2787 mentioned in the Introduction as the only structural design method in existence for stormwater chambers. The standard, however, is almost entirely in U.S. Customary Units which will not work internationally, so I would like to convert it to metric leaving inch/pound values in parentheses. The plan is to do the conversions without altering the technical content of the standard. Doing this will ensure that ASTM F2787 is the default international standard for the structural design of stormwater chambers.